It is previously known in the art to activate Ziegler-Natta polymerization catalysts, particularly such catalysts comprising Group 3-10 metal complexes containing delocalized π-bonded ligand groups, by the use of an activator. Generally in the absence of such an activator compound, also referred to as a cocatalyst, little or no polymerization activity is observed. A class of suitable activators are aluminoxanes, or alkylaluminoxanes, which are generally believed to be oligomeric or polymeric alkylaluminoxy compounds, including cyclic oligomers. Generally such compounds contain, on average about 1.5 alkyl groups per aluminum atom, and are prepared by reaction of trialkylaluminum compounds or mixtures of compounds with water (Reddy et al, Prog. Poly. Sci., 1995, 20, 309-367). The resulting product is in fact a mixture of various substituted aluminum compounds including especially, trialklyaluminum compounds (resulting from incomplete reaction of the trialkylaluminum starting reagent or decomposition of the alumoxane). The amount of such free trialkylaluminum compound in the mixture generally varies from 1 to 50 percent by weight of the total product. Examples of alumoxanes include methylalumoxane (MAO) made by hydrolysis of trimethylaluminum as well as modified methylalumoxane (MMAO), made by hydrolysis of a mixture of trimethylaluminum and triisobutylaluminum. While such activators normally are soluble in hydrocarbons (homogeneous cocatalyst), supported versions may be prepared by fixing the alumoxane to a solid, particulated substrate. Silica having alumoxane, particularly methylalumoxane, chemically bonded thereto, presumably by reaction to form a silicon/oxygen/aluminum bond, is also well known and commercially available. Disadvantageously, such a heterogeneous, supported cocatalyst does not demonstrate significant cocatalytic efficiency due in part possibly to the oligomeric nature and low Lewis acidity of alumoxane.
A different type of activator compound is a Bronsted acid salt capable of transferring a proton to form a cationic derivative or other catalytically active derivatiive of such a Group 3-10 metal complex. Examples of such Bronsted acid salts are protonated ammonium, sulfonium, or phosphonium salts capable of transferring a hydrogen ion, disclosed in U.S. Pat. Nos. 5,198,401, 5,132,380, 5,470,927, and 5,153,157, as well as oxidizing salts such as lead, silver, carbonium, ferrocenium and silyilium salts, disclosed in U.S. Pat. Nos. 5,350,723, 5,189,192 and 5,626,087. Supported or polyionic salt activators disclosed in U.S. Pat. No. 5,427,991 are prepared by chemically binding a plurality of such salt anions to a core component. Disadvantageously, activation of a neutral metal complex by means of a proton transfer mechanism unavoidably produces a neutral by-product, such as an amine, that can interfere with subsequent catalyst activity.
Further suitable activators for the above metal complexes include strong Lewis acids including (trisperfluorophenyl)borane and tris(perfluorobiphenyl)borane. The former composition has been previously disclosed for the above stated end use in EP-A-520,732, and elsewhere, whereas the latter composition is disclosed in Marks, et al., J. Am. Chem. Soc., 118, 12451-12452 (1996). Additional teachings of the foregoing activators may be found in Chen, et al, J. Am. Chem. Soc. 1997, 119, 2582-2583, Jia et al, Organometallics, 1997, 16, 842-857. and Coles et al, J. Am. Chem. Soc. 1997, 119, 8126-8126. All of the foregoing Lewis acid activators in practice are based on perfluorophenyl substituted boron compounds. Use of such activator compounds in a supported catalyst system has met with limited success due to the difficulty in retaining the activator on the support surface.
In U.S. Pat. No. 5,453,410, an alumoxane, particularly methylalumoxane, was disclosed for use in combination with constrained geometry, Group 4 metal complexes, especially in a molar ratio of metal complex to alumoxane of from 1/1 to 1/50. This combination beneficially resulted in improved polymerization efficiency. Similarly, in U.S. Pat. Nos. 5,527,929, 5,616,664, 5,470,993, 5,556,928, 5,624,878, various combinations of metal complexes with trispentafluorophenyl boron cocatalyst, and optionally an alumoxane, were disclosed for use as catalyst compositions for olefin polymerization.
U.S. Pat. No. 5,763,547 discloses a slurry polymerization process using a supported catalyst formed by slurrying a silica/alumoxane support with a solution of a monocyclopentadienyl Group IV metal complex in ISOPAR E, and subsequently briefly contacting with a borane activator.
WO 97/44371 discloses a gas phase polymerization process using a supported catalyst formed by contacting a dried or calcined silica support (optionally pretreated with water) with triethylaluminum, slurrying the support with toluene and contacting with a solution of a borane, and subsequently contacting with a solution of a monocyclopentadienyl Group IV metal complex in toluene. Representative polymer compositions disclosed demonstrated improved rheological performance, and a rising comonomer distribution.
WO 97/43323 discloses slurry polymerization processes utilizing a supported catalyst formed by depositing a monocyclopentadienyl Group IV metal complex and a perfluorophenyl borate onto a dried and/or calcined silica support which has been passivated with a trialkylaluminum compound. Representative polymer compositions demonstrated a rising comonomer distribution.
EP 824112A1 discloses a supported composition wherein a Group IIIA metal-containing compound is directly (or through a spacer) covalently bonded to a moiety on the support, which compound may be of neutral or ionic construction, and which forms a catalyst system with a transition metal compound, such as a metallocene. Although aluminum-containing compounds are broadly disclosed as suitable Group IIIA metal-containing compounds, no example describes their use; nor do any teachings recognize any unexpected utility of aluminum-containing species.
U.S. Pat. No. 5,643,847 discloses a catalyst composition comprising a metal oxide support having a counter anion derived from a Lewis acid not having readily hydrolyzable ligands (such as a tri-perfluorophenyl borane) covalently bound to the surface of the support directly through the oxygen atom of the metal oxide, wherein the anion is also ionically bound to a catalytically active transition metal compound.
It would be desirable if there were provided functionalized catalyst supports, more particularly, it would be desirable if there were provided a functionalized support material adapted to chemically bind the metal complex, especially a Group 4 metal complex to the surface thereof and to supported catalyst systems obtainable from the activation of a metal complex using such functionalized catalyst supports, for use in olefin polymerizations that could be employed in slurry, solid phase, gas phase or high pressure polymerizations.